The present embodiments relate to ultrasound imaging. In particular, the fat fraction in tissue is estimated using ultrasound. Nonalcoholic fatty liver disease (NAFLD) is the most common liver disease in American adults and children. NAFLD is characterized by excess hepatic fat accumulation as well as hepatic fibrosis. Magnetic resonance imaging (MRI) accurately measures the proton density fat fraction (PDFF) as a biomarker of hepatic fat content. However, MRI is not widely available and expensive. An ultrasound-based technique to quantify liver fat may advance clinical care.